At least 43 people died Friday in what authorities described as a fierce, three-hour gunbattle between federal forces and suspected drug gang gunmen on a ranch in western Mexico, the deadliest such confrontation in recent memory.

All the dead were suspected criminals except for one federal police officer, National Security Commissioner Monte Alejandro Rubido said. He said the officer died trying to help a colleague wounded in the shootout.

Photographs from the scene showed bodies, some with semi-automatic rifles and others without weapons, lying in fields, near farm equipment and on a blood-stained patio strewn with clothes, mattresses and sleeping bags. Video obtained by The Associated Press showed federal police coming under fire and bodies strewn throughout a ranch.

Rubido said the suspects were members of "a criminal organization operating in Jalisco state," but did not mention the Jalisco New Generation, the drug cartel that dominates the area where the battle erupted and has grown rapidly in recent years to become one of Mexico's biggest organized crime groups.

Rubido said the confrontation started Friday morning in the municipality of Tanhauto on the border between Jalisco and Michoacan states when soldiers, federal police and state and federal investigators responded to a report of the sudden appearance of armed men on a ranch. During the operation, federal forces encountered a truck full of armed men who opened fire and when they chased the gunmen onto the ranch, they came under heavy fire by others, he said.

"The rest of the presumed criminals on the property started to attack with intensity," Rubido said.

The federal force called for air and ground support, which included a police helicopter. The size of the ranch, 277 acres, complicated the battle, which lasted for three hours, Rubido said.

He said the investigation continued but that so far authorities had detained three people and confiscated 36 semi-automatic weapons, two smaller arms, a grenade launcher that had been fired and a .50-caliber rifle.

The lop-sided results were similar to a controversial case last June 30 in which Mexico's army said its troops had engaged in a shootout with alleged criminals in which 22 suspects were killed but only one soldier injured. An investigation by The Associated Press revealed that many of suspects had been killed after they surrendered.

Rubido emphasized that both state and national human rights teams were dispatched immediately to investigate Friday's bloodshed at the ranch, which residents of the area said is called Rancho del Sol.

The border of Michoacan and Jalisco states is an area dominated by the Jalisco New Generation cartel and it has been the scene of numerous incidents of cartel violence in recent years.

In the nearby town of La Barca, authorities in 2013 found more than five dozen bodies in mass graves linked to the Jalisco cartel. In 2014, gunmen killed the mayor of a nearby town, Tanhuato.

Jalisco New Generation has mounted several large-scale attacks on federal and state forces in recent weeks.

In April, gunmen believed linked to the cartel ambushed a police convoy in Jalisco, killing 15 state officers and wounding five. Earlier this month, New Generation gunmen shot down a military helicopter with a rocket launcher in Jalisco, killing eight aboard.

In just a few years, New Generation has grown from a small faction of the powerful Sinaloa cartel to one of Mexico's strongest criminal groups in its own right, according to the U.S. Treasury Department, whose Office of Foreign Assets Control maintains a "black list" of drug trafficking organizations.

New Generation's quick rise reflects a rapidly changing organized-crime landscape in Mexico as the government targets top leaders of established cartels. More than any other criminal group, New Generation has taken advantage of the government strategy, strengthening and grabbing territory as its rivals are weakened.